A-LevelPhysicsElectric fields9702/22 · Oct/Nov 2020 · Q77 Marks

State a similarity and a difference between an up quark and an up antiquark.

(a)State a similarity and a difference between an up quark and an up antiquark.[2]
(b)(i)An electron in an electric field, in a vacuum, at an instant when the electron is stationary. [Figure 7.1] On Fig. 7.1, draw an arrow to show the direction of the electric force acting on the stationary electron.[1]
(b)(ii)The electric field causes the electron to move from its initial position. Describe and explain the acceleration of the electron due to the field, as the electron moves through the field.[2]
(b)(iii)A stationary α-particle is now placed in the same electric field at the same initial position that was occupied by the electron. Compare the initial electric force acting on the α-particle with the initial electric force that acted on the electron.[2]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.

[B1] similarity: same/equal mass / or same/equal (magnitude of) charge / or both fundamental (particles)
[B1] difference: opposite (sign of) charge / or one is matter and the other is antimatter
[B1] arrow points to the right
[B1] (electric) field strength increases / or (electric) force increases
[B1] acceleration increases
[B1] force (on α-particle) has twice the magnitude (of force on electron)
[B1] force (on α-particle) is in opposite direction (to force on electron)

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